Gunmen in Indian-administered Kashmir raked a construction site work camp with bullets, killing seven people and wounding several others, Indian media reported Monday, updating an earlier toll.
The attack on Sunday is one of the worst this year targeting civilians.
The contested territory's chief minister, Omar Abdullah, called the attack late Sunday "dastardly and cowardly", while India's interior minister Amit Shah vowed those responsible would face the "harshest" response.
Muslim-majority Kashmir has been divided between rivals India and Pakistan since their independence from British rule in 1947, and is home to a long-running insurgency.
Attackers targeted workers from outside the Himalayan region, who were reported to be building a tunnel connecting Kashmir with the far northern Ladakh region.
Among the seven killed was a doctor, the Press Trust of India (PTI) news agency reported on Monday, adding several others were wounded.
Abdullah, who was sworn in as the region's chief minister on Wednesday after its first local elections for a decade, said he strongly condemned the attack on "non-local labourers".
Soon after the attack, Abdullah confirmed two people had been killed but had warned there were also "a number of injured labourers, both local and non-local".
At least 500,000 Indian troops are deployed in Kashmir, battling an insurgency with tens of thousands of civilians, soldiers and rebels killed since 1989.
India's home minister Amit Shah called the killings "a despicable act of cowardice", in a statement.
"Those involved in this heinous act will not be spared, and will face the harshest response from our security forces," Shah said.
The attack took place Gagangir in Sonamarg region, where Nitin Gadkari, India's minister of roads said the "innocent labourers" had been working on a "vital infrastructure project".
Gunmen fired automatic weapons at the camp from forested hills around, Indian newspapers reported.
India regularly accuses Pakistan of supporting and arming the rebels, a charge Islamabad denies.
Indian Prime Minister Narendra Modi's government cancelled Kashmir's limited autonomy in 2019, accompanied by mass arrests and a months-long communications blackout.
His administration says the decision has allowed it to stem the insurgency, but critics have accused it of suppressing political freedoms.
Nine Indian Hindu pilgrims were killed and dozens more wounded in June when a gunman opened fire on a bus carrying them from a shrine in Reasi district.
